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NAME
address_families - socket address families (domains)
SYNOPSIS
#include <sys/types.h> /* See NOTES */
#include <sys/socket.h>
int socket(int domain, int type, int protocol);
DESCRIPTION
The domain argument of the socket(2) specifies a communication domain; this selects the protocol family
which will be used for communication. These families are defined in <sys/socket.h>. The formats
currently understood by the Linux kernel include:
AF_UNIX, AF_LOCAL
Local communication For further information, see unix(7).
AF_INET
IPv4 Internet protocols. For further information, see ip(7).
AF_AX25
Amateur radio AX.25 protocol. For further information, see ax25(4).
AF_IPX IPX - Novell protocols.
AF_APPLETALK
AppleTalk For further information, see ddp(7).
AF_NETROM
AX.25 packet layer protocol. For further information, see netrom(4), The Packet Radio Protocols
and Linux and the AX.25, NET/ROM, and ROSE network programming chapters of the Linux Amateur Radio
AX.25 HOWTO.
AF_BRIDGE
Can't be used for creating sockets; mostly used for bridge links in rtnetlink(7) protocol
commands.
AF_ATMPVC
Access to raw ATM Permanent Virtual Circuits (PVCs). For further information, see the ATM on
Linux HOWTO.
AF_X25 ITU-T X.25 / ISO-8208 protocol. For further information, see x25(7).
AF_INET6
IPv6 Internet protocols. For further information, see ipv6(7).
AF_ROSE
RATS (Radio Amateur Telecommunications Society) Open Systems environment (ROSE) AX.25 packet layer
protocol. For further information, see the resources listed for AF_NETROM.
AF_DECnet
DECet protocol sockets. See Documentation/networking/decnet.txt in the Linux kernel source tree
for details.
AF_NETBEUI
Reserved for "802.2LLC project"; never used.
AF_SECURITY
This was a short-lived (between Linux 2.1.30 and 2.1.99pre2) protocol family for firewall upcalls.
AF_KEY Key management protocol, originally developed for usage with IPsec (since Linux 2.1.38). This has
no relation to keyctl(2) and the in-kernel key storage facility. See RFC 2367 PF_KEY Key
Management API, Version 2 for details.
AF_NETLINK
Kernel user interface device For further information, see netlink(7).
AF_PACKET
Low-level packet interface. For further information, see packet(7).
AF_ECONET
Acorn Econet protocol (removed in Linux 3.5). See the Econet documentation for details.
AF_ATMSVC
Access to ATM Switched Virtual Circuits (SVCs) See the ATM on Linux HOWTO for details.
AF_RDS Reliable Datagram Sockets (RDS) protocol (since Linux 2.6.30). RDS over RDMA has no relation to
AF_SMC or AF_XDP. For further information see rds(7), rds-rdma(7), and
Documentation/networking/rds.txt in the Linux kernel source tree.
AF_IRDA
Socket interface over IrDA (moved to staging in Linux 4.14, removed in Linux 4.17). For further
information see irda(7).
AF_PPPOX
Generic PPP transport layer, for setting up L2 tunnels (L2TP and PPPoE). See
Documentation/networking/l2tp.txt in the Linux kernel source tree for details.
AF_WANPIPE
Legacy protocol for wide area network (WAN) connectivity that was used by Sangoma WAN cards
(called "WANPIPE"); removed in Linux 2.6.21.
AF_LLC Logical link control (IEEE 802.2 LLC) protocol, upper part of data link layer of ISO/OSI
networking protocol stack (since Linux 2.4); has no relation to AF_PACKET. See chapter 13.5.3.
Logical Link Control in Understanding Linux Kernel Internals (O'Reilly Media, 2006) and IEEE
Standards for Local Area Networks: Logical Link Control (The Institute of Electronics and
Electronics Engineers, Inc., New York, New York, 1985) for details. See also some historical
notes regarding its development.
AF_IB InfiniBand native addressing (since Linux 3.11).
AF_MPLS
Multiprotocol Label Switching (since Linux 4.1); mostly used for configuring MPLS routing via
netlink(7), as it doesn't expose ability to create sockets to user space.
AF_CAN Controller Area Network automotive bus protocol (since Linux 2.6.25). See
Documentation/networking/can.rst in the Linux kernel source tree for details.
AF_TIPC
TIPC, "cluster domain sockets" protocol (since Linux 2.6.16). See TIPC Programmer's Guide and the
protocol description for details.
AF_BLUETOOTH
Bluetooth low-level socket protocol (since Linux 3.11). See Bluetooth Management API overview and
An Introduction to Bluetooth Programming by Albert Huang for details.
AF_IUCV
IUCV (inter-user communication vehicle) z/VM protocol for hypervisor-guest interaction (since
Linux 2.6.21); has no relation to AF_VSOCK and/or AF_SMC See IUCV protocol overview for details.
AF_RXRPC
Rx, Andrew File System remote procedure call protocol (since Linux 2.6.22). See
Documentation/networking/rxrpc.txt in the Linux kernel source tree for details.
AF_ISDN
New "modular ISDN" driver interface protocol (since Linux 2.6.27). See the mISDN wiki for
details.
AF_PHONET
Nokia cellular modem IPC/RPC interface (since Linux 2.6.31). See
Documentation/networking/phonet.txt in the Linux kernel source tree for details.
AF_IEEE802154
IEEE 802.15.4 WPAN (wireless personal area network) raw packet protocol (since Linux 2.6.31). See
Documentation/networking/ieee802154.txt in the Linux kernel source tree for details.
AF_CAIF
Ericsson's Communication CPU to Application CPU interface (CAIF) protocol (since Linux 2.6.36).
See Documentation/networking/caif/Linux-CAIF.txt in the Linux kernel source tree for details.
AF_ALG Interface to kernel crypto API (since Linux 2.6.38). See Documentation/crypto/userspace-if.rst in
the Linux kernel source tree for details.
AF_VSOCK
VMWare VSockets protocol for hypervisor-guest interaction (since Linux 3.9); has no relation to
AF_IUCV and AF_SMC. For further information, see vsock(7).
AF_KCM KCM (kernel connection multiplexer) interface (since Linux 4.6). See
Documentation/networking/kcm.txt in the Linux kernel source tree for details.
AF_QIPCRTR
Qualcomm IPC router interface protocol (since Linux 4.7).
AF_SMC SMC-R (shared memory communications over RDMA) protocol (since Linux 4.11), and SMC-D (shared
memory communications, direct memory access) protocol for intra-node z/VM quest interaction (since
Linux 4.19); has no relation to AF_RDS, AF_IUCV or AF_VSOCK. See RFC 7609 IBM's Shared Memory
Communications over RDMA (SMC-R) Protocol for details regarding SMC-R. See SMC-D Reference
Information for details regarding SMC-D.
AF_XDP XDP (express data path) interface (since Linux 4.18). See Documentation/networking/af_xdp.rst in
the Linux kernel source tree for details.
SEE ALSO
socket(2), socket(7)
COLOPHON
This page is part of release 5.10 of the Linux man-pages project. A description of the project,
information about reporting bugs, and the latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
Linux 2018-10-16 ADDRESS_FAMILIES(7)